Vasoactive intestinal peptide (VIP) mediates the effect of estrogens on the dopaminergic tone in the hypothalamic-pituitary axis of ovariectomized (OVX) rats |
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| Authors: | Mercedes Lasaga Adriana Seilicovich Daniel Pisera María del Carmen Díaz Marcelo F Befumo and Beatriz H Duvilanski |
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| Institution: | (1) Centro de Investigaciones en Reproducción, Facultad de Medicina, Piso 10, Universidad de Buenos Aires, 1121 Buenos Aires, Argentina |
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| Abstract: | The role of vasoactive intestinal peptide (VIP) in the regulation of dopamine (DA) concentration in mediobasal hypothalamus
(MBH), posterior and anterior pituitary of ovariectomized (OVX) estrogenized rats was studied using passive immunization against
VIP with a specific antiserum (a-VIP). Chronic estradiol administration decreased DA concentration in MBH, and in posterior
and anterior pituitary, compared to OVX control rats. DA tissue concentration increased following a-VIP administration to
control and estrogenized OVX rats. In vitro study of VIP and a-VIP on DA release from MBH in chronically estrogenized OVX
rats showed that estrogens decreased DA evoked-release from MBH; a-VIP increased DA evoked-release from MBH of control OVX
and estrogenized rats. VIP decreased DA evoked-release from MBH of OVX rats, but had no effect on estrogenized rats. VIP decreased
DA tissue concentration in MBH of OVX control but not of estrogenized rats. It is suggested that VIP decreases DA synthesis
and release from hypothalamic neurons in female rats, and that VIP partially mediates the inhibitory effect of long-term estrogen
administration on DA release from MBH. |
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| Keywords: | Vasoactive intestinal peptide (VIP) dopamine (DA) estradiol mediobasal hypothalamus (MBH) pituitary gland |
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